We plan to investigate the effect of acute periods of protein deprivation on the ability of a lymphohematopoietic system injured by systemic cancer therapy to repair and restore itself. Our preliminary studies of the ability of transplanted bone marrow to repopulate a lethally irradiated mouse have demonstrated that in the presence of no protein intake, there is marked suppression of hematopoiesis. The studies proposed herein will examine the quantitative effect of graded doses of dietary protein to restore normal repopulation kinetics of transplanted bone marrow. Studies will also be carried out to examine quantitatively the effect of graded amounts of dietary protein on the ability of autologous residual bone marrow CFUs and CFUc to repopulate the mouse after sublethal systemic chemotherapy and irradiation. Using the adoptive transfer system, we will determine quantitatively the effect of those same protein deficient diets on the ability of syngeneic immunocompetent cells to recover. These studies will be extended to the study of the replicative ability of CFUs, CFUc, and their progeny from murine bone marrow cultured in diffusion chambers implanted into mice maintained for a short period of time on graded protein diets. Marrow from normal humans and patients with leukemia in varying states of remission and relapse will be grown in diffusion chambers implanted into chemotherapy and/or radiation treated mice that are subjected to dietary manipulation. The effect of these diets on the chamber total and differential cell count, as well as the content of CFUc will be determined.